Kids invent magic.

In every culture, children invent fantasies to entertain themselves and explain things they don't understand. We note from study that the fantasies are typically fabricated from other things they know, and are full of fallacies.

Adult mythology is also composed of familiar ideas, and history and science show these to be full of fallacies too. All that changes is that while kids get over their fantasies, some adults take them seriously for the rest of their lives.

It gives no strong evidence of anything they say.

Firstly, the volume of religions is more of a observation of human psychology and sociology than proof of a good. People form groups for comfort and security and always have for the whole of history. In the past this was justified by survival, now it is justified by a communal belief. It also shows that humans need to feel accepted, which isn't a bad thing, but doesn't prove a god at all.

Also, to put it into context, if I created a sect with the main belief that purple rainbow-tailed unicorns flew across the sky all the time and it gained massive support and spread worldwide, that doesn't prove that purple rainbow-tailed unicorns exist.

No. It does not support it.

The reason that the multitudes of religious beliefs refutes this, is that if all these religions exist, contradicting each other, claiming that their gods or beings or beliefs are the one true religious aspects in the world then all of them are denying each other. The possibility if you consider the facts, is that there is a 1% chance that there is a higher power.